Induction clutch



1949 D. SENSAUD DE LAVAUD ETAL 2,483,079

" INDUCTION CLUTCH Filed Dec. 26, 1945 1). @maud DeLava/w C E. JIzLLcZePatented Nov. 15, 1949 2,488,079 INDUCTION CLUTCH Dimitri Sensaud deLavaud and Charles Emmanuel Mlld, Paris, France Application December 26,1945, Serial No. 637,223 In France April 17, 1945 4 Claims. 1

In the usual electromagnetic clutches hitherto known the engagement iseffected by means of magnetic induction or attraction between, on onepart, a driving inductor component formed by a homopolar magnetic bodykeyed to one shaft and provided with hollows in which are disposedconductors to constitute a squirrel cage, and, on the other part, amagnetic metal driven component or crown which is keyed to another shaftand provided with a holed rim and of which the relative rotation withrespect to said driving component produces variations of magnetic flux.

When such clutches are applied to the automobile traction, it isexpedient to make the driving shaft carry practically the most part, ifnot all, of the rotating masses. hence to secure the inductor componentto the driving shaft and key to the driven shaft the hollowed crown theinertia of which is reduced. The drivinginductor component body thussubstitutes itself for the usual fly wheel of the thermo-motor.

It is an object of the present invention to further reduce in weight thecrown keyed to the driven shaft, by substituting for the hollowedmagnetic metal crown a non-magnetic material crown having a peripheralrim provided with hollows into which are fitted small bars of magneticmetal, preferably embedded therein in the process of making, to formapparent poles of the component secured to the driven shaft.

Such crown may be made from any suitable non-magnetic material such, forexample as light alloys; it may also be made from a non-metallicinsulating material, preferably by molding.

Hollowed crowns made from magnetic metal have a known disadvantage incausing magnetic leakage and reducing the amplitude of flux variations,facts that decrease the intensity of induced currents, hence the torque.

It is therefore a further object of this invention to provide a novelcrown such as to reduce as much as possible magnetic leakage andincrease the amplitude of flux variations, hence the torque.

It will, of course, be possible, particularly with a view to increasingthe torque at starting and in normal operation, as has already beenproposed for devices of this kind. to provide several conductors in thesquirrel cage per apparent pole of the crown.

Other objects of the present invention will be apparent from thefollowing description dealing with an example of a non-magnetic metalcrown comprising magnetic elements or small bars, applied to a squirrelcage asynchronous clutch and constituting the driven crown component ofan induction clutch improved according to the invention.

The invention will be described with reference to the accompanyingdiagrammatic drawings in which:

Fig. 1 is a general axial sectional view showing the crown designedaccording to the invention;

Fig. 2 is a fragmentary sectional view through the line 11-11 of Fig. 1;

Fig. 3 is a fragmentary plan view of the crown with its apparent poles.

According to the invention, the clutch crown is cast from any suitablenon-magnetic material such for example as certain known light alloys. Inthe mould containing the pattern there are disposed a desired number ofsmall bars i of magnetic material, such for example as soft iron, whichbars, after the metal is cast, remain embedded in the cast mass of acylindric rim 2. The longitudinal and transversal sections of such barsare determined, as illustrated by Figs. 1 and 2. so as to cause them tostay fixed in the mass of cast material and keep so in despite ofcentrifugal magnetic deflections liable to be exerted thereupon.

In the example shown, the bars are inclined with respect to thecorresponding radial planes, as illustrated by Fig. 3; this contributesto the silent operation of the clutch. The width and distribution of thebars I define the width and distribution of apparent poles of the rim 2or operational part of the crown engaged into the magnetic flux of theinductor component, formed by a magnetic body keyed on a drive shaft 5|,which magnetic body includes the elements 54, 54a, and 54b havingsquirrel cages comprising polar pieces Sic, Blb, conducting rings 63aand 63b, through which the winding 56 develops a magnetic fieldindicated generally by the line ill.

The crown is centered and secured by its cheek-plate 3 to a hub 4 as bymeans of rivets 5, which permits this component to be keyed to thedriven shaft 53 of the clutch.

Finally, there are provided weight reducing and ventilation openings 6in the rim 2 between the bars i, and similar openings 1 in thecheekplate 3.

What we claim is:

1. Electromagnetic clutch comprising in combination driving and drivenshafts a magnetic homopolar inductor fitted with squirrel cages andkeyed to one of said shafts, and a holed crown keyed to the other ofsaid shafts and producing. when relatively rotated with respect to saidinductor, variations of magnetic flux, said crown each bar correspondseveral conductors in the being made from non-magnetic material andhaving a peripheral rim provided with spaced holes, and small bars ofmagnetic material lodged in said holes and forming apparent poles ofsaid OI'OWII.

2. Electromagnetic clutch comprising in combination driving and drivenshafts a magnetic homopolar inductor fitted with squirrel cages andkeyed to one of said shafts, and a holed crown keyed to the other ofsaid shafts and producing, when relatively rotated with respect to saidinductor, variations of magnetic flux, said crown being made fromnon-magnetic material and having a peripheral rim, and spaced small barsof magnetic material embedded in said rim, said bars forming apparentpoles of said crown.

3. Electromagnetic clutch comprising in combination driving and drivenshafts a magnetic homopolar inductor fitted with squirrel cages andkeyed to one of said shafts, and a holed crown keyed to the other ofsaid shafts and producing. when relatively rotated with respect to saidinductor, variations of magnetic flux, said crown being made fromnon-magnetic material and having a peripheral rim, and spaced small barsof magnetic material on said rim, said bars forming apparent poles ofsaid crown so that to squirrel cage.

4. Electromagnetic clutch comprising in combination driving and drivenshafts a magnetic homopolar inductor fitted with squirrel cages andkeyed to one of said shafts. and a holed crown keyed to the other ofsaid shafts and producing, when relatively rotated with respect to saidinductor, variations of magnetic flux, said crown being made fromnon-magnetic material and having a peripheral rim, and spaced bars ofmagnetic material on said rim, said bars being inclined with respect tocorresponding radial planes 0; said crown and forming apparent polesthere- 0 DIMITRI BENSAUD or LAVAUD. CHARLES EMMANUEL Mnmt.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,357,517 Burdick Sept. 5, 19442,392,148 Hornbostel Jan. 1, 1946 2,396,000 Findley Mar. 5, 19462,409,557 Gilflllan Oct. 15, 1948

